tbuckley/cabot-search huggingface dataset:
Abstract P3186: Mcub Is An Inducible Regulator Of Calcium-dependent Mitochondrial Metabolism
Authors: Jiuzhou Huo, Vikram Prasad, Kelly Grimes, Davy Vanhoutte, Scott Blair, Michael Bround, Donald M Bers, Jeff D Molkentin
Journal: Circulation Research (2023)

Summary: Mitochondria use the electron transport chain to generate high energy phosphate from oxidative phosphorylation of fuel substrates, and the regulation of this process is critical for metabolic homeostasis. Notably, acute influx of Ca 2+ across the inner mitochondrial membrane through the mitochondrial Ca 2+ uniporter (MCU) augments the activity of several electron transport chain dehydrogenases and the F 1 F 0 ATP synthase. However, recent results with deletion of the Mcu gene in mice, which prevents acute Ca 2+ influx, shows the unanticipated effect of augmenting total mitochondrial oxidative phosphorylation and weight loss in mice. Here we determined that the MCU complex gene product Mcub , which is a direct inhibitor of MCU mediated Ca 2+ influx, is induced by caloric restriction in heart, skeletal muscle, liver and kidney, where it functions as a metabolic activator of mitochondrial fatty acid utilization. Here we performed skeletal muscle-specific deletion of MCUb mice to directly investigate the role of MCUb in substrate utilization. Mice lacking Mcub in skeletal muscle showed a metabolic signature of increased pyruvate dehydrogenase activity, increased muscle malonyl CoA, deficient fatty acid utilization, total glucose intolerance, and metabolic syndrome with increased fat deposition. By comparison, fasting induces mitochondrial MCUb expression to reduce mitochondrial Ca 2+ uptake, which results in greater fatty acid oxidation in skeletal muscle. Mechanistically, PDK4 was decreased in muscle of MCUb deleted mice, and overexpression of PDK4 abolished these altered substrate preferences as observed with MCUb deletion in skeletal muscle. Thus, MCUb serves as an inducible control point in regulating skeletal muscle mitochondrial Ca 2+ , which impacts total body metabolism, weight gain and metabolic syndrome.
Abstract P3173: Exposure Of Mitochondria Isolated From Left Ventricular Myocardium Of Dogs With Moderate Heart Failure To 4-hydroxy-2-nonenal (4-hne) Worsens Existing Mitochondrial Dysfunction
Authors: VINITA SINGH-GUPTA, Ramesh C Gupta, Kristina Castle, Kefei Zhang, Jiang Xu, Hani N Sabbah
Journal: Circulation Research (2023)

Background: Reactive oxygen species (ROS) generated by dysfunction of mitochondria (MITO) of the failing heart plays an important role in lipid peroxidation of polyunsaturated fatty acids in cell and MITO membranes resulting in the production of aldehydes, such as malondialdehyde and 4-hydroxy-2-nonenal (4-HNE). MITO aldehyde dehydrogenase-2 (mALDH2) is a key enzyme for the detoxification of endogenous aldehyde substrates through NAD dependent oxidation. We previously showed that mALDH2 expression and activity are markedly reduced in MITO of failing LV cardiomyocytes, a maladaptation that can lead to considerable accumulation of 4-HNE in MITO. It is unclear whether such an accumulation of 4-HNE can further exacerbate MITO dysfunction resulting in further limitation to ATP formation via oxidative phosphorylation. Hypothesis: This study tested the hypothesis that exposure of MITO isolated from failing hearts to exogenous 4-HNE can result in further deterioration of MITO function. Methods: Freshly isolated MITO from LV myocardium of dogs with moderate heart failure (HF, LV ejection fraction ~40%) were incubated for 1 hour in absence (baseline) and presence of 4-HNE at concentrations of 3 and 30 μM. MITO energetic parameters namely ADP-stimulated respiration (ADPresp), maximal respiratory capacity (MRC) and ATP-linked respiration (ATPresp) were evaluated using an XFe96 analyzer (Seahorse Biosciences). Results: Compared to baseline, exposure of MITO to 3 μM 4-HNE has no significant effects on any of the MITO energetic measures. However, exposure of MITO to 30 μM 4-HNE resulted in significant reduction of ADPresp (490 ± 37 vs. 179 ± 7 OCR pmols/O 2 /min, p&lt;0.05), significant reduction of MRC (334 ± 56 vs. 124 ± 18 OCR pmols/O 2 /min, p&lt;0.05), and significant reduction of ATPresp (48 ± 10 vs. 20 ± 12 OCR pmols/O 2 /min, p&lt;0.05). Conclusions: Exposure of MITO from failing myocardium to elevated levels of 4-HNE can lead to marked deterioration of MITO function that can result in a further reduction of ATP leading to progression of LV dysfunction. Limiting the accumulation of 4-HNE through pharmacologic normalization of ALDH2 activity can potentially represent a therapeutic target for retarding the progression of LV dysfunction toward intractable HF.
Abstract P3091: Suppression Of Myeloid Yap Antagonizes Adverse Cardiac Remodeling During Pressure Overload Stress
Authors: Jamie Francisco, Dominic Del Re
Journal: Circulation Research (2023)

Inflammation is an integral component of cardiovascular disease and is thought to contribute to cardiac dysfunction and heart failure. While ischemia-induced inflammation has been extensively studied in the heart, relatively less is known regarding cardiac inflammation during non-ischemic stress. Recent work has implicated a role for Yes-associated protein (YAP) in modulating inflammation in response to ischemic injury; however, whether YAP influences inflammation in the heart during non-ischemic stress is not described. We hypothesized that YAP mediates a pro-inflammatory response during pressure overload (PO)-induced non-ischemic injury, and that targeted YAP inhibition in the myeloid compartment is cardioprotective. In mice, PO elicited myeloid YAP activation, and myeloid-specific YAP knockout mice (YAP F/F ;LysM Cre ) subjected to PO stress had preserved systolic function, and attenuated pathological remodeling compared to control mice. Inflammatory indicators were also significantly attenuated, while pro-resolving genes including Vegfa were enhanced, in the myocardium of myeloid YAP KO mice after PO. Experiments using bone marrow-derived macrophages (BMDMs) from YAP KO and control mice demonstrated that YAP suppression shifted polarization toward a resolving phenotype. We also observed attenuated NLRP3 inflammasome priming and function in YAP deficient BMDMs, as well as in myeloid YAP KO hearts following PO, indicating disruption of inflammasome induction. Studies in RAW264.7 cells demonstrated the effectiveness of pharmacological YAP inhibition using verteporfin to attenuate pro-inflammatory gene expression, and augment VEGFA levels. Finally, we leveraged nanoparticle-mediated delivery of verteporfin and observed attenuated PO-induced pathological remodeling and inflammation compared to DMSO nanoparticle control treatment. These data implicate myeloid YAP as an important molecular nodal point that facilitates cardiac inflammation and fibrosis during PO stress and suggest that selective inhibition of YAP may prove a novel therapeutic target in non-ischemic heart disease.
Abstract P2027: Chronic β-Adrenergic Receptor Stimulation Exacerbates Left Ventricular Dilation And Myocardial Cell Death In Rgs2 Knockout Mice
Authors: Shelby Dahlen
Journal: Circulation Research (2023)

Sustained sympathoexciation and increased circulating catecholamine level are hallmarks of congestive heart failure. Elevated catecholamine level promotes a sustained β -adrenergic receptor (βAR) stimulation in the myocardium, altering the balance between cell death and survival via intracellular signaling downstream of G s - and G i/o -class G proteins. Previously, we and others reported that moderation of Gα i activity by regulators of G protein signaling (RGS) 2 and 5 separately is key to maintaining normal ventricular rhythm. Here, using single isogenic wild type (WT), Rgs2 -/- , Rgs5 -/- , and Rgs2/5 double knockout (dbKO) adult male mice with or without systemic isoproterenol infusion, we determined whether a compensatory relationship between RGS2 and RGS5 is cardioprotective and promotes myocardial cell survival during chronic sympathoexcitation. We found that basal heart weight-to-tibia-length (HW/TL) ratio of both Rgs2 and dbKO mice was elevated relative to WT control. Echocardiography revealed left ventricular dilation in all three KO genotypes, as evidenced by increased left ventricular internal diameter and volume. Both Rgs2 -/- and Rgs5-/- mice displayed reduced ejection fraction and fractional shortening. To explore the mechanism mediating the LV dilation, we challenged the mice with chronic βAR stimulation by systemic isoproterenol infusion (ISO, 30 mg/kg/day) for 3 or 14 days via subcutaneous osmotic mini-pumps. ISO infusion substantially increased HW/TL ratio in WT mice after day 3, while HW/TL ratio in Rgs2 -/- and dbKO mice was increased with exacerbated LV dilation. After 14-day ISO infusion, only dbKO mice displayed increased lung weight/TL ratio, indicating a congestive heart failure. Additionally, myocardial tissue from saline treated dbKO mice had a larger number of TUNEL + cells that was further increased by ISO infusion, with extensive interstitial fibrosis as visualized with Masson trichrome staining, and increased expression of heart failure biomarkers Mybpc3 and Tnni3 . Taken together, we conclude that the loss of R gs2, more-so than Rgs5, predisposes to myocardial cell death and rapid progression to dilated cardiomyopathy and heart failure during sustained sympathoexciation and β-adrenergic stimulation.
Abstract P2126: Role Of Microrna-98 In Myocardial Ischemia-reperfusion Injury In Late Pregnancy
Authors: Laila Aryan, Lejla Medzikovic, Min Li, Gregoire Ruffenach, Shadie Rahman, Ehsan Bastanhagh, Leana Esdin, Wasila Sun, Yalda A Afshar, Mansoureh Eghbali
Journal: Circulation Research (2023)

Background: We have shown that the late-pregnant (LP) rodent is more vulnerable to myocardial ischemia-reperfusion injury (IRI) compared to non-pregnant (NP). The molecular mechanisms are unknown. Several microRNAs (miRs) are dysregulated in IRI, making them promising therapeutic targets. Methods: The left anterior descending coronary artery (LAD) of female Sprague-Dawley rats (2-3 months old NP and LP, 20-21 days pregnant) was occluded for 45 minutes followed by 3 hours reperfusion. Myocardial necrosis was assessed using TTC staining. MicroRNA-microarray profiling was performed on hearts of NP and LP rats subjected to IRI. In vitro, female cardiomyocytes were transfected either miR98 mimic or inhibitor, followed by 3 hours hypoxia and 6 hours reoxygenation. Blood samples were collected from NP, LP, and coronary heart disease (CHD) patients. To assess therapeutic potential of miR, miR98 inhibitor was administered at the onset of reperfusion. Results: MicroRNA-microarray profiling revealed miR-98-5p (miR-98) is upregulated in the hearts of LP IRI rats compared to NP IRI by 2.3 folds, which we confirmed with qPCR. miR98 is significantly increased in the plasma of healthy LP compared to healthy NP women, and significantly increased in LP with CHD compared to healthy LP. TargetScan revealed STAT3 and PGC-1α to be targets of miR98. We confirmed significantly decreased expression of STAT3 and PGC-1α in LP IRI rat myocardium compared to NP IRI. MiR98 overexpression in female cardiomyocytes subjected to hypoxia/reoxygenation (H/R) decreased STAT3 and PGC-1α, and increased apoptosis, inflammation, and oxidative stress, while miR-98 knockdown resulted in the opposite effect. Therapeutic targeting of microRNA-98-5p in LP rats subjected to IRI reduced infarct size, apoptosis, oxidative stress, and inflammatory markers via upregulating Stat3 and Pgc-1α. Conclusions: MiR98 is upregulated in LP rats subjected to IRI compared to NP IRI and in LP human plasma samples with CHD compared to healthy NP and LP. miR98 promotes oxidative stress, inflammation, and apoptosis in the setting of H/R in vitro by targeting STAT3 and PGC-1α. Inhibition of miR-98 in LP rats reduces myocardial infarct size, apoptosis, oxidative stress, and inflammation via Stat3 and Pgc-1α.
Abstract GS.08: Cardiolipin Is A Novel Target Of Therapy To Mitigate Myocardial Injury Due To Veno-arterial Extracorporeal Membrane Oxygenation (va-ecmo)
Authors: Navin K Kapur, Lija Swain, Shreyas Bhave, Xiaoying Qiao, Lara A Reyelt, Elena Mahmoudi, Kay Everett, Mary Warner, Junya Awata, Michael T Chin
Journal: Circulation Research (2023)

Cardiolipin (CL) is a mitochondrial specific phospholipid that maintains integrity of the electron transport chain (ETC) and plays a central role in myocardial ischemia-reperfusion injury. VA-ECMO use to provide hemodynamic support for acute myocardial infarction (AMI) has grown exponentially; is associated with poor outcomes; and is the subject of active clinical trials, yet the mechanistic impact of VA-ECMO on myocardial damage in AMI remains poorly understood. We hypothesized that VA-ECMO acutely depletes myocardial CL and promotes myocardial damage in AMI. We first report that levels of CL and tafazzin, a key enzyme required for CL synthesis, are significantly reduced in the left ventricles (LV) of human subjects requiring VA-ECMO compared to subjects without VA-ECMO prior to heart transplantation. Six hours of exposure to VA-ECMO also decreased LV levels of CL and tafazzin in healthy swine compared to sham controls. To explore whether CL depletion by VA-ECMO increases infarct size, we performed left anterior descending artery (LAD) occlusion for a total of 120 minutes followed by 180 minutes of reperfusion in adult swine in the presence and absence of MTP-131, an amphipathic molecule that interacts with CL to stabilize the inner mitochondrial membrane. Compared to reperfusion alone, VA-ECMO activation beginning after 90 minutes of LAD occlusion increased infarct size (33±11% vs 48±7%, p&lt;0.001). VA-ECMO also decreased CL and tafazzin levels, disrupted mitochondrial structural integrity, reduced ETC function and promoted oxidative stress. Compared to reperfusion alone or VA-ECMO before reperfusion, intracoronary delivery of MTP-131 five minutes before VA-ECMO activation reduced infarct size (22±8%, p=0.03 vs IRI and p&lt;0.001 vs VA-ECMO). Treatment with MTP-131 also restored CL and tafazzin levels, stabilized mitochondrial function, and reduced oxidative stress in the LV. Our results identify a novel mechanism by which VA-ECMO promotes myocardial dysfunction and further identify cardiolipin as an important target of therapy to reduce infarct size and preserve mitochondrial function for patients requiring VA-ECMO for acute myocardial infarction. Future clinical studies are required to test the translational utility of this approach.
Abstract P3163: Exosomes From Pseudomonas Aeruginosa Infected Macrophages Drives Cardiomyocyte Contractile Dysfunction
Authors: Naresh Kumar, Omar S Ahumada, Maneeth P Ellendula, Clara Planner, Mahmood Khan, Harpreet Singh, Sahil Mahajan, William Lafuse, Daniel Wozniak, Latha Ganesan, Murugesan V Rajaram
Journal: Circulation Research (2023)

Rationale: Pseudomonas aeruginosa ( P.a. ) infection is very common in ICU patients and is known to increase the mortality rate. Our lab demonstrated that P.a. infection caused severe cardiac dysfunction without disseminating into the heart. However, the mechanism of cardiac complication during P. a. infection is not known; understanding this is critical for the development of host-protective therapy. Thus, we hypothesize that cardiac dysfunction caused by P.a. is either mediated through systemic inflammation and/or the release of exosomes and bacterial outer membrane vesicles from infected cells. Objective: Identify the mechanism of cardiac inflammation and cardiac dysfunction caused by P.a. infection. Methods and Results: To investigate whether P.a. infection causes cardiomyocyte contractile dysfunction, we exposed the hiPSC-CMs with P.a. and monitored the hiPSC-CMs electrical activity using Multi-electrode array (MEA). We found that the contraction of hiPSC-CMs stopped completely at 8h post-infection. Next, to test whether the inflammatory cytokines, exosomes, and bacterial OMVs released upon infection affect contractile function, we exposed the hiPSC-CMs with conditioned media harvested from P.a. infected hMDMs. Our data revealed that exposure of conditioned media to hiSPC-CMs caused severe contractile dysfunction and arrhythmia. Also, we found that conditioned media contains an increased level of inflammatory cytokines IL-1β, TNFα, and IL-6 along with exosomes and OMVs. To test whether heat inactivation of conditioned media preserves the hiPSC-CMs, we inactivated the media and stimulated the cells. Our data suggest that the heat-inactivated conditioned media impaired the hiPSC-CMs contractility, due to the release of exosomal content. Furthermore, based on LC-MS/MS analysis of purified exosomes from P.a. infected hMDMs, we identified that exosomes are packed with bacterial toxins and immunogenic antigens. Conclusion: Our data demonstrate that P.a. releases OMVs and bacterial toxins into the host cells, which are packed in exosomes. Though, infected macrophages release inflammatory cytokines, the main source for hiPSC-CM contractile dysfunction is the release of exosomes packed with bacterial toxins and antigens.
Abstract P3050: <i>Cpne5</i> Is Necessary For Normal Murine Sinoatrial Node Function <i>In Vivo</i>
Authors: Lu Ren, Phung Thai, Sruthi Mantri, Lauren Duan, Felix Atzert, Benjamin Beyersdorf, Nipavan Chiamvimonvat, Sean M Wu, William R Goodyer
Journal: Circulation Research (2023)

Cpne5 ( Copine 5 ) is a Ca 2+ -dependent phospholipid binding protein implicated in membrane trafficking but has no known role within the heart to date. In single-cell RNA-sequencing of the developing mouse heart, we previously found Cpne5 gene expression to be highly enriched in the cardiac conduction system (CCS). Further, variants in CPNE5 were identified in 6 independent GWAS related to heart rate variability in humans. We therefore hypothesized that Cpne5 is necessary for normal CCS function through Ca 2+ -dependent membrane trafficking of ion channels. Whole mount immunostaining with 3D volumetric imaging (iDISCO+) of intact WT hearts demonstrated robust and specific protein expression of Cpne5 throughout all CCS components, including the sinoatrial node (SAN) and SAN-transitional cells. Next, to assess the necessity of Cpne5 within the CCS, systemic knockout mice (Cpne5KO) were generated using CRISPR/Cas9. Successful deletion of Cpne5 in CRISPR-generated KO mice was confirmed by PCR and, at the protein level, immunofluorescence. Homozygous Cpne5KO mice were viable, showed normal growth and allele frequencies segregated in a normal Mendelian fashion. No gross anatomic defects of the CCS were observed in Cpne5KO mice and transthoracic echocardiogram studies showed a slight reduction in left ventricular fractional shortening but otherwise a structurally normal heart. Notably, while surface electrocardiogram (ECG) demonstrated normal intervals (PR, QRS, QTc), Cpne5KO mice exhibited pronounced sinus arrhythmia, with notable sinus pauses, sinus bradycardia, and increased heart rate variability as compared to WT littermate controls on long term telemetry. Systemic loss-of-function of Cpne5 in mice resulted in marked sinus node dysfunction, consistent with human GWAS data, implicating a novel role for Cpne5 in CCS function and/or development. Additional phenotyping and molecular studies, including CPNE5 deletion in human induced-pluripotent cell-derived SAN-like cells, are ongoing to further elucidate its underlying mechanism.
Abstract P1152: Molecular Regulation Of Ferroptosis In The Type 1 Diabetic Heart
Authors: Flobater I Gawargi
Journal: Circulation Research (2023)

Background/Hypothesis: The molecular mechanisms underpinning ferroptosis, a newly emerged mechanism of myocardial cell death, remains unclear in the T1DM heart. Although the targeted deletion of matrix metalloproteinase-9 (MMP9) is cardioprotective, the role of MMP9 in T1DM-induced cardiac ferroptosis is unknown. We hypothesize that the lack of MMP9 mitigates ferroptosis in the T1DM heart. Methods/Results: We randomly selected 15-week-old male Ins2 +/- Akita (T1DM) and age and gender-matched Ins2 +/+ littermate WT mice to examine T1DM-induced cardiac ferroptosis. We used our novel Akita/MMP9KO (DKO) mice to investigate the specific effect of MMP9 deficiency on T1DM-induced cardiac ferroptosis. Following the guidelines on myocardial cell death , we evaluated ferroptosis in the heart (LV) of WT, Akita, DKO, and MMP9KO mice. The comparison of protein levels in (i) Akita vs. WT and (ii) Akita vs. DKO (n=3-6) revealed that the lack of MMP9 prevents T1DM-induced upregulation of iron import [Transferrin Receptor (TFR): (i) +2.44-fold, (ii) -1.78-fold], downregulation of iron export [Ferroportin-1: (i) -3.20-fold, (ii) +2.20-fold], amplification of lipid peroxidation via a decrease in Glutathione Peroxidase-4 (GPX4) [(i) -1.95-fold, (ii) +2.01-fold], antioxidants [ {Superoxide dismutase-1 (SOD1): (i) -1.1-fold, (ii) +1.00-fold} and SOD2 {(i) -1.58-fold, (ii) +1.01-fold}], and an increase in Lysophosphatidylcholine Acyltransferase-3 (LPCAT3) [(i) +3.14-fold, (ii) -2.09-fold] in the heart. Conclusion: We reveal the mechanisms by which MMP9 deficiency mitigates ferroptosis in the T1DM heart (Figure 1). This is the first report of MMP9 role in cardiac ferroptosis.
Abstract P2005: Mechanosensitive Piezo-1 Channel Aggravates Ischemia Induced Adverse Cardiac Remodeling And Dysfunction
Authors: Prachi Umbarkar, Sulivette Ruiz Ramirez, Suma Ejantkar, Sultan Tousif, Angelica Toro Cora, Cristi L Galindo, Qinkun Zhang, Hind Lal
Journal: Circulation Research (2023)

Background: Mechanotransduction is a physiological process through which mechanical forces are sensed and converted to biological responses. It is fundamental for morphogenesis during early development and organ functions during adult life. An injured heart undergoes dynamic phases of structural and functional remodeling, exposing cardiac cells to the fluctuating mechanical environment. Piezo-1 (PZO1) is a recently discovered mechanosensitive ion channel with widespread physiological importance. However, its role in the pathophysiology of heart disease is not fully understood. Methods and Results: The qPCR analysis confirmed that PZO-1 expression increases in cardiomyocytes (CM) post-MI. To evaluate the role of CM-PZO1 in MI-induced adverse cardiac remodeling, conditional CM-specific PZO1 KO mice were generated using tamoxifen-inducible α-MHC promoter driven MerCreMer transgene. At 12 weeks of age, mice were subjected to a well-established tamoxifen diet protocol followed by MI surgery. Cardiac function was monitored by serial echocardiography. In the control group, EF and FS declined from 2 weeks post-MI, indicating systolic dysfunction. These changes were associated with the development of structural remodeling as reflected by a significant increase in LVIDs, HW/TL ratio, CM CSA, and hypertrophy markers (ANP, BNP). Interestingly, all these parameters were essentially normalized in CM-PZO1 KO mice, confirming that CM-specific PZO1 deletion prevents the progression of pathological hypertrophy and systolic dysfunction in MI heart. Moreover, CM-PZO1 KO displayed significant alterations in gene expression of ECM proteins such as connective tissue growth factor (CTGF), latent TGF-β binding protein 2 (LTBP2), cartilage oligomeric matrix protein (COMP), cartilage intermediate layer protein (CILP) while collagen and fibronectin levels were comparable between control and KO groups. These observations indicate a potential role of CM-PZO1 in modulating cardiac ECM and scar properties under pathological conditions. Conclusion: Our findings suggest that PZO1 serves as a key cardiac mechanotransducer under pathological condition and represent a novel therapeutic target for treating heart diseases.